The four chambers of the human heart are the right atrium, left atrium, right ventricle, and left ventricle. The heart has valves (mitral and tricuspid) between the atria and the ventricles and has valves (aortic and pulmonary) in the arteries leaving the heart. These heart valves generally maintain the unidirectional flow of blood by opening and closing depending on difference in pressure on each of their sides. Various heart conditions are treated by surgically replacing one or more of the heart's valves with bio-prosthetic (e.g., tissue-based valves from pigs, cows, etc.) or artificial prosthetic valves (e.g., metal, etc.). For example, such prosthetic valves are often surgically inserted to treat aortic stenosis. Aortic stenosis occurs where a normal aortic valve, which is generally circular with three leaflets that open or close a relatively large orifice, becomes stenatic over time such that its leaflets become calcified, the aortic valve cannot fully open, and the flow of blood is restricted.
A common method of treating aortic stenosis uses open-heart valve surgery that generally involves opening the chest, stopping the heart, opening the heart and sewing in a prosthetic valve with usually from fifteen to eighteen sutures to replace the stenatic valve. The stenatic valve's leaflets may be cut and some or all of the calcification cut away to allow more room for the inserted prosthetic valve. The prosthetic valve typically has a sewing ring or solid annulus through which the sutures are threaded during surgery. While sewing these sutures to secure a valve does not usually take a long time, the use of sutures generally requires a sternotomy, which is a procedure that typically involves a vertical incision along the breastbone, division or cracking of the breastbone itself, and results in long patient recovery periods. Without such a sternotomy, the surgeon's task of sewing in the sutures can be difficult and, for example, may involve the surgeon having to look and/or work through a small hole while inserting the sutures.
Various suture-less prosthetic valves have been used. Generally, however, fixative devices used with such prosthesis have been unsatisfactorily with respect to allowing the inserted valve to leak or move. Such failures make such valves more risky (e.g., in terms of patient mortality, etc.) than the valves deployed using suture-based techniques. Recently, for example, percutaneous valves have been deployed without sutures using a one-shot deployment technique that does not allow adjustment after deployment. For example, a catheter can be introduced across the valve, the valve dilated, positioned, and expanded, for example, with a nitinol (nickel titanium) support. As the valve expands, it is held in place. However, once the valve has been so deployed, it cannot be adjusted. The deployment is permanent until the valve is surgically removed, for example, by cutting it out and, thereafter, the same valve cannot be redeployed. If the percutaneous valve itself becomes calcified, removal can be hampered by its permanent deployment mechanisms and may result in the unwanted cracking of calcification that results in loose material in the heart.